A mobile communication system includes a radio access network (RAN) and a core network (CN). Typically, the RAN includes a radio base station apparatus that directly communicates with a mobile terminal, and a control apparatus that controls the radio base station apparatus. Further, the CN serves as a switching equipment of speech communication and packet communication.
The radio base station apparatus in the mobile communication system is operated after execution of various tests and setting of various parameters. Accordingly, the radio base station apparatus is able to provide a service area, which is an environment where communication is possible, for a mobile terminal.
Meanwhile, a technique of reducing power consumption by a radio base station apparatus has recently been attracting attention. This is due to the strong demands for reduction in cost of communication not only in typical radio base station apparatuses but also in radio base station apparatuses that are provided by general consumers or corporations at home or offices.
A patent literature 1 discloses a technique related to reduction in power consumption by a radio base station apparatus. FIG. 23 is a diagram for describing a radio base station apparatus according to the patent literature 1. In FIG. 23, a radio base station apparatus 100 includes a controller 120 that transmits/receives a signal 170 to/from a network 160, and signal processors 130_1 to 130_5 respectively transmitting/receiving transmission/reception signals 171_1 to 171_5 to/from the controller 120. The radio base station apparatus 100 further includes a transmitter/receiver 140 that transmits/receives transmission/reception signals 172_1 to 172_5 transmitted/received to/from these signal processors to/from a mobile terminal through an antenna 150. The controller 120 controls the signal processors 130_1 to 130_5 by transmitting/receiving control signals 181_1 to 181_5, respectively, and controls the transmitter/receiver 140 by a control signal 182. Further, the controller 120 is connected to a terminal number estimation unit 110, and acquires an estimated value of the number of terminals using a signal 180.
In the radio base station apparatus shown in FIG. 23, the terminal number estimation unit 110 estimates the number of mobile terminals present in a service area on the basis of the number of location registrations of the mobile terminals, the number of access request messages from the mobile terminals, or the number of incoming call notification messages to the mobile terminals. Further, the controller 120 turns off power supplies of unnecessary signal processors 130_1 to 130_5 on the basis of the estimated number of the mobile terminals.
Further, a patent literature 2 discloses a technique related to a mobile radio antenna control system using a global positioning system (GPS). FIG. 24 shows the mobile radio antenna control system disclosed in the patent literature 2. In FIG. 24, a base station 209 includes a base station apparatus 205, an antenna direction/transmission output control apparatus 206, a base station receiving antenna 208, and a base station transmitting antenna 207. Further, a mobile station 204 includes a mobile station apparatus 201, a location detection apparatus 202, and a mobile station antenna 203.
The mobile radio antenna control system according to the patent literature 2 calculates at which location the mobile station 204 is present based on the location information received by the base station apparatus 205. The patent literature 2 discloses a technique that the base station apparatus 205 transmits radio waves having directivity in an optimum transmission direction with an optimum transmission output in consideration of the location of the mobile station 204.
Further, patent literatures 3 to 6 disclose a technique related to power saving in a radio communication system and a radio base station apparatus.